Display device with touch panel

ABSTRACT

A touch panel includes X electrodes which extend in a same direction, and Y electrodes which extend in a direction different from the direction of the X electrodes. The X electrodes and the Y electrodes respectively include intersection portions each formed where the X electrodes and the Y electrodes overlap each other, and electrode portions each formed between the intersection portions, wherein the electrode portions of one of the X electrodes is smaller in area than the electrode portions of one of the Y electrodes, and wherein dummy electrodes are formed close to the electrode portion of one of the X electrode or the Y electrodes.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.12/493,391, filed Jun. 29, 2009, now U.S. Pat. No. 8,217,916, thecontents of which are incorporated herein by reference.

The present application claims priority from Japanese applicationJP2008-169816 filed on Jun. 30, 2008, the content of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device with a touch panel,and more particularly, to a technology effectively applicable to adisplay device with a touch panel that is a capacitive touch panel.

2. Description of the Related Art

In recent years, a touch panel technology that supports human-consciousgraphical user interfaces has played a pivotal role in prevalence ofmobile equipment.

As the touch panel technology, a capacitive touch panel is known. As thecapacitive touch panel, JP 2003-511799 A discloses a touch panel thatdetects a touch point touched by an observer's finger.

The touch panel described in JP 2003-511799 A detects the coordinates ofa point touched by an observer through detection of a couplingcapacitance between an electrode in an X direction and an electrode in aY direction.

SUMMARY OF THE INVENTION

A common capacitive touch panel includes a plurality of X electrodeswhich extend in a first direction (for example, Y direction) and areplaced next to one another in a second direction (for example, Xdirection) intersecting the first direction, and a plurality of Yelectrodes which extend in the second direction to intersect the Xelectrodes and are placed next to one another in the first direction.Touch panels of this type are called X-Y touch panels.

The plurality of X electrodes and the plurality of Y electrodes in anX-Y touch panel are formed on a substrate with an interlayer insulatingfilm interposed between the X electrode layer and the Y electrode layer.Those X electrodes and Y electrodes are formed of a transparentconductive material such as indium tin oxide (ITO).

In X-Y touch panels of the related art, the capacitance of one line ofelectrodes in a steady state where the touch panel is not being touchedby a finger or the like includes an inter-electrode capacitance with anadjacent electrode, an intersection capacitance formed at theintersection of orthogonal electrodes, and a ground capacitance with adisplay device placed under the touch panel.

An index of their detection sensitivity, which is the ratio of a changein capacitance that is caused by a touch of a finger or the like tobackground noise (hereinafter referred to as S/N ratio), is used.Raising the detection sensitivity, i.e., the S/N ratio, requiresincreasing signals or reducing noise.

The signal level is in proportion to the capacitance that is formedbetween a finger or the like touching the touch panel and an electrode.A fact found about background noise is that the fluctuations in voltageof a signal generated by the display device in order to display an imageare detected as noise by electrodes of the touch panel which is locatedright above the display device. It is easier to detect the noise whenthe total electrode area along one line of electrodes is larger becausethe ground capacitance is accordingly larger.

The touch panel overlaid on the display device when in use hassubstantially the same contour as that of the display device. Thedisplay device generally has a rectangular shape which is longer in theX direction or in the Y direction.

In the related art, individual electrodes constituting one line in the Xdirection and individual electrodes constituting one line in the Ydirection are equal in size whereas one line of electrodes in the Xdirection and one line of electrodes in the Y direction differ from eachother in length and in the number of individual electrodes constitutingone line. The capacitance of one line of electrodes in the X directiontherefore differs from the capacitance of one line of electrodes in theY direction. To give an example, in the case of a touch panel verticallylong, the capacitance of one line of X electrodes which are arrangedparallel to one another in the Y direction is larger than thecapacitance of one line of Y electrodes which are arranged parallel toone another in the X direction.

The difference in capacitance along one line of electrodes between the Xdirection and the Y direction means that the noise intensity differsbetween the X direction and the Y direction in touch panels of therelated art. In other words, the S/N ratio differs between the Xdirection and the Y direction in touch panels of the related art.

Therefore the overall detection sensitivity of the touch panel isdefined by the lower one of the differing S/N ratios.

The present invention has been made in view of described above, and anobject of the present invention is therefore to provide a display devicewith a touch panel that has a large S/N ratio and a high detectionsensitivity.

The above-mentioned and other objects of the present invention, as wellas novel features of the present invention, become clear through adescription given herein and the accompanying drawings.

The inventors of the present invention have found out that, in touchpanels of the related art, the noise intensity ratio of the X electrodesto the Y electrodes is substantially equal to the X electrode-to-Yelectrode capacitance ratio, namely, X electrode-to-Y electrode countratio.

The present invention is based on the above-mentioned findings. Theabove-mentioned object is attained by: reducing the area of eachindividual electrode on a line of electrodes that runs along the longersides of an input region of a touch panel; setting the ratio of the areaof each individual electrode on this line of electrodes to the area ofeach individual electrode on another line of electrodes, which isorthogonal to the former line of electrodes, to a value smaller than theratio of the electrode count of the line of electrodes that runs alongthe input region's longer side direction to the electrode count of theline of electrodes that runs along the input region's shorter sidedirection by 10% or less so that the capacitance along one line ofelectrodes is substantially equal to the capacitance along the otherline of electrodes; and disposing floating electrodes (dummy electrodes)in places freed up by the area reduction.

Of aspects of the present invention disclosed herein, representativeones are briefly described as follows:

(1) A display device with a touch panel, which includes: a displaypanel; and a capacitive touch panel formed to be overlaid on the displaypanel, and is characterized in that: the touch panel includes Xelectrodes and Y electrodes which intersect the X electrodes; the Xelectrodes and the Y electrodes include intersection portions at whichthe X electrodes and the Y electrodes overlap each other, and electrodeportions each formed between two of the intersection portions; and oneof the electrode portions of the X electrode and the electrode portionsof the Y electrode is smaller in area than another thereof so that acapacitance of one line of the X electrodes and a capacitance of oneline of the Y electrodes are equal to each other.

(2) A display device with a touch panel, which includes: a displaypanel; and a capacitive touch panel bonded onto the display panel, andis characterized in that: the touch panel includes X electrodes and Yelectrodes which intersect the X electrodes; the display panel haslonger sides and shorter sides; the X electrodes and the Y electrodesinclude intersection portions at which the X electrodes and the Yelectrodes overlap each other, and individual electrodes each formedbetween two of the intersection portions and being wider than theintersection portions; the X electrodes are formed along the longersides whereas the Y electrodes are formed along the shorter sides; andeach individual electrode of the X electrodes is smaller in area thaneach individual electrode of the Y electrodes.

(3) A display device with a touch panel, which includes: a displaypanel; and a capacitive touch panel placed on the display panel, and ischaracterized in that: the touch panel includes X electrodes and Yelectrodes which intersect the X electrodes; the X electrodes and the Yelectrodes include intersection portions at which the X electrodes andthe Y electrodes overlap each other, and individual electrodes eachformed between two of the intersection portions and being wider than theintersection portions; the a number of the individual electrodes of theX electrodes is n and a number of the individual electrodes of the Yelectrodes is m; and a ratio between an area of the individualelectrodes of the X electrodes and an area of the individual electrodesof the Y electrodes is m:n.

The advantageous effect that are obtained by the representative ones ofthe aspects of the present invention disclosed herein are summarized asfollows.

According to the present invention, there can be provided a displaydevice with a touch panel that has a large S/N ratio and a highdetection sensitivity.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a plan view illustrating a schematic structure of a displaydevice with a touch panel according to an embodiment of the presentinvention;

FIG. 2 is a sectional view illustrating a sectional structure takenalong the line A-A′ of FIG. 1;

FIG. 3 is a plan view illustrating an electrode pattern of a capacitivetouch panel according to the embodiment of the present invention;

FIG. 4 is a graph illustrating a change in S/N ratio of a capacitivetouch panel when an area of each individual electrode of X electrodes,which is arranged parallel to each other in a longitudinal direction, isvaried;

FIG. 5 is a sectional view illustrating a sectional structure of theline B-B′ at the first step of the method of manufacturing the touchpanel according to the embodiment of the present invention;

FIG. 6 is a sectional view illustrating the sectional structure of theline B-B′ at the second step of the method of manufacturing the touchpanel according to the embodiment of the present invention;

FIG. 7 is a sectional view illustrating the sectional structure of theline B-B′ at the third step of the method of manufacturing the touchpanel according to the embodiment of the present invention;

FIG. 8 is a sectional view illustrating the sectional structure of theline B-B′ at the fourth step of the method of manufacturing the touchpanel according to the embodiment of the present invention;

FIG. 9 is a sectional view illustrating a sectional structure of theline C-C′ at the first step of the method of manufacturing the touchpanel according to the embodiment of the present invention;

FIG. 10 is a sectional view illustrating the sectional structure of theline C-C′ at the second step of the method of manufacturing the touchpanel according to the embodiment of the present invention;

FIG. 11 is a sectional view illustrating the sectional structure of theline C-C′ at the third step of the method of manufacturing the touchpanel according to the embodiment of the present invention;

FIG. 12 is a sectional view illustrating the sectional structure of theline C-C′ at the fourth step of the method of manufacturing the touchpanel according to the embodiment of the present invention;

FIG. 13 is a diagram illustrating a state in which an observer's fingeris touching the touch panel according to the embodiment of the presentinvention;

FIG. 14 is a diagram illustrating an operation of detecting an inputpoint of the touch panel according to the embodiment of the presentinvention;

FIG. 15 is a plan view illustrating an electrode pattern of anothertouch panel to which the present invention is applied; and

FIG. 16 is a sectional view illustrating a sectional structure takenalong the line A-A′ of FIG. 15.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention is described below in detail withreference to the drawings.

Throughout the drawings for describing the embodiment of the presentinvention, components that have the same function are denoted by thesame reference symbol in order to avoid repetitive description.

The description of this embodiment takes a liquid crystal display panelas an example of a display panel. Any display panel can be employed aslong as it allows the use of a touch panel and, other than liquidcrystal display panels, display panels that use organic light emittingdiode elements or surface conduction electron emitter elements areemployable.

FIG. 1 is a plan view illustrating a schematic structure of a displaydevice with a touch panel according to the embodiment of the presentinvention. FIG. 2 is a sectional view taken along the line A-A′ of FIG.1.

A display device with a touch panel 300 of this embodiment includes, asillustrated in FIGS. 1 and 2, a liquid crystal display panel 600, acapacitive touch panel 400 which is placed on an observer side of theliquid crystal display panel 600, and a backlight 700 which is placed onthe opposite side of the liquid crystal display panel 600 from theobserver side. The liquid crystal display panel 600 can be, for example,an in plane switching (IPS) liquid crystal display panel, a twistednematic (TN) liquid crystal display panel, or a vertical alignment (VA)liquid crystal display panel.

The liquid crystal display panel 600 is formed by bonding together twosubstrates that are opposed to each other. Polarizing plates 601 and 602are provided on the exteriors of the two substrates.

The liquid crystal display panel 600 and the touch panel 400 are bondedto each other with a first bonding member 501 which is a resin film, anadhesive film, or the like. A second bonding member 502 which is a resinfilm, an adhesive film, or the like bonds a front surface protectingplate (also called front window) 12 made of an acrylic resin to theexterior of the touch panel 400.

A transparent conductive layer 603 is provided between the liquidcrystal display panel 600 and the polarizing plate 601. The transparentconductive layer 603 is formed to shield against signals generated bythe liquid crystal display panel 600. A large number of electrodes areprovided on the liquid crystal display panel 600 and voltages areapplied as signals to the electrodes on various timings.

A change in voltage on the liquid crystal display panel 600 is noise toelectrodes that are provided on the capacitive touch panel 400. Theliquid crystal display panel 600 therefore needs to be electricallyshielded, and this is why the transparent conductive layer 603 isprovided. In order to function as a shield, the transparent conductivelayer 603 receives a supply of a constant voltage from a flexibleprinted board 71 or others, and is set to, for example, a groundpotential.

The transparent conductive layer 603 desirably has a sheet resistancevalue approximately equal to that of the electrodes provided on thetouch panel 400, specifically, 150 to 200 Ω/square, for reducing theinfluence of the noise. The resistance value of the transparentconductive layer 603 is known to have a relation with the crystal grainsize. The transparent conductive layer 603 can have a sheet resistancevalue of 150 to 200 Ω/square by setting the heat treatment temperatureto 200° C. or higher for crystallizing.

The transparent conductive layer 603 may have an even lower resistance.For example, setting the heat treatment temperature to 450° C. andthereby crystallizing the transparent conductive layer 603 thoroughlygives the transparent conductive layer 603 a sheet resistance value of10 to 40 Ω/square. The effect of reducing the noise is improved when theshielding transparent conductive layer 603 has a resistanceapproximately equal to, or lower than that of the electrodes provided onthe touch panel 400. In the case of an IPS liquid crystal display panelwhere a reverse-surface side transparent conductive film is formedbetween the liquid crystal display panel 600 and the polarizing plate601, the reverse-surface side transparent conductive film may also havea function as the transparent conductive layer 603.

A drive circuit 50 is provided across from one of the four sides of theliquid crystal display panel 600, and supplies various signals to imageelements inside the liquid crystal display panel 600. A flexible printedboard 72 is connected to one of the four sides of the liquid crystaldisplay panel 600 in order to supply signals from the outside. Thesignals are supplied from the outside to the drive circuit 50 via theflexible printed board 72.

Another flexible printed board 71 is connected to the touch panel 400. Atouch panel control circuit 60 is mounted to the flexible printed board71 to control the detection of an input point and other operations.

A spacer 30 is placed between the touch panel 400 and the drive circuit50.

FIG. 3 is a plan view illustrating the electrode structure of the touchpanel 400 according to this embodiment. FIG. 3 illustrates a case ofusing the touch panel 400 vertically long. The liquid crystal displaypanel 600 overlaid with the touch panel 400 similarly has a shapevertically long as mentioned above.

A glass substrate 5 is employed as a transparent substrate. Touch panelelectrodes (1 and 2), connection terminals 7, wiring lines 6 extendingfrom the touch panel electrodes (1 and 2) to the connection terminals 7are placed on one surface of the glass substrate 5. At leastintersection portions of the two touch panel electrodes (1 and 2)arranged orthogonally to each other are separated by an insulating film.

The touch panel electrodes (1 and 2) are formed of a transparentconductive film. Of the touch panel electrodes (1 and 2), electrodesthat extend in the longitudinal direction (Y direction of FIG. 3) andare arranged side by side in the lateral direction (X direction) arecalled X electrodes 1, whereas electrodes that extend in the lateraldirection (X direction) to intersect the X electrodes 1 and are arrangedside by side in the longitudinal direction (Y direction) are called Yelectrodes 2. The touch panel 400 of this embodiment detects a change incapacitance of those X electrodes 1 and Y electrodes 2 to calculate apoint where the touch panel 400 has been touched. A region inside thedotted line, which is denoted by reference numeral 3 and capable ofdetection, is called an input region.

The X electrodes 1 and the Y electrodes 2 are narrower in intersectionportions 1 a and intersection portions 2 a, respectively, and wider inelectrode portions 1 b and electrode portions 2 b, respectively. Eachelectrode portion 1 b is sandwiched between two intersection portions 1a and each electrode portion 2 b is sandwiched between two intersectionportions 2 a. The electrode portion 1 b sandwiched between theintersection portions 1 a and the electrode portion 2 b sandwichedbetween the electrode portions 2 a are also called individualelectrodes.

In the touch panel 400 of this embodiment, the individual electrodes 1 bof the X electrodes 1 are narrower than the individual electrodes 2 b ofthe Y electrodes 2 as illustrated in FIG. 3. In other words, the area ofthe X electrodes 1 is made smaller in a manner that reflects the ratioof the count of the individual electrodes 1 b of the X electrodes 1 tothe count of the individual electrodes 2 b of the Y electrodes 2, andthe X electrodes 1 are divided into the individual electrodes 1 b andelectrodes (dummy electrodes) 4 which have a floating potential.

In this way, the electrode area of the X electrodes 1 which would belarger as the vertical length of the panel's shape is longer is reducedsuch that the capacitance along one line of X electrodes 1 issubstantially equal to the capacitance along one line of Y electrodes 2.The X electrodes 1 and the Y electrodes 2 are thus made equal in termsof noise that is caused by fluctuations in voltage of a signal generatedby the liquid crystal display panel 600.

As mentioned above, the transparent conductive layer 603 provided on theliquid crystal display panel 600 reduces the influence of the noise fromthe liquid crystal display panel 600. However, forming the transparentconductive layer 603 on the liquid crystal display panel 600 at hightemperature is difficult and, in some cases, it is not possible to formthe transparent conductive layer 603 that has sufficiently lowresistance on the liquid crystal display panel 600. Further, even withthe transparent conductive layer 603, the noise from the liquid crystaldisplay panel 600 can still influence.

FIG. 4 is a graph illustrating results of an S/N ratio evaluation on thetrial touch panel 400 by varying the area of each individual electrode 1b along an X electrode line parallel to the longitudinal direction. Thetrial touch panel 400 has six X electrodes 1, ten Y electrodes 2, anX-to-Y electrode count ratio of 60%, and a shape vertically long. InFIG. 4, the axis of abscissa indicates the area ratio of each individualelectrode 1 b to each individual electrode 2 b, and the axis of ordinateindicates the S/N ratio.

As illustrated in FIG. 4, when the area of the individual electrode 1 bbecomes smaller and the floating electrodes are formed, the groundcapacitance decreases and the noise level can be reduced. When one ofthe X electrodes 1 reduced in area is touched with a finger or the like,the floating electrodes 4 adjacent to the touched X electrode 1 are alsotouched and caused to function by capacitance coupling. The degree ofthe signal level reduction is therefore smaller than the degree of thearea reduction.

The resultant S/N ratio therefore has peaked at an area ratio that isequal to the electrode count ratio as illustrated in FIG. 4.

In the case where the floating electrodes 4 are not provided, aninterval 8 between one X electrode 1 and its adjacent Y electrode 2 islarger than when the floating electrodes 4 are provided. The interval 8is a region that includes the insulating film and the glass substratebut does not include the transparent conductive film of which the Xelectrodes 1 and the Y electrodes 2 are formed as mentioned above. Aportion that includes the transparent conductive film and a portion thatdoes not include the transparent conductive film differ from each otherin terms of transmittance, reflectance, and chromaticity of reflectedlight, and hence the interval 8 is visible to the naked eye, whichlowers the quality of the displayed image.

According to our study, the interval 8 has been faintly visible when itis 30 μm wide, hardly visible at 20 μm, and invisible at 10 μm.Narrowing the interval 8 increases the capacitance between the Xelectrode 1 and the Y electrode 2 that are adjacent to each other withthe floating electrode 4 interposed therebetween. Narrowing the interval8 also increases defects in which unsuccessful pattern formation due toa foreign object attached in the process of manufacture results in ashort-circuit between the X electrode 1 or the Y electrode 2 and thefloating electrode 4.

A short-circuit of the floating electrode 4 adjacent to the individualelectrode 1 b of one X electrode 1 causes inconveniences such as anincrease in ground capacitance of the relevant one line of X electrodes,increased noise, and a decrease in detection sensitivity.

In order to reduce an increase in capacitance that is caused by theshort-circuit, each floating electrode 4 is a ¼ piece of a whole asillustrated in FIG. 3. Dividing each floating electrode 4 into morepieces lowers the risk of a short-circuit defect, but increases theregions that do not have the transparent conductive film, which mayincrease the difference in transmittance, reflectance, and chromaticitybetween adjacent electrodes. This embodiment therefore chooses to divideeach floating electrode 4 into four and set the interval between theelectrodes narrower than 30 μm, specifically, to 20 μm or so.

This embodiment shows a case of overlaying a touch panel on a liquidcrystal display device vertically long, but the effects of the presentinvention are similarly obtained when the touch panel is overlaid on aliquid crystal display device vertically long, or on other types ofimage display device. Further, the number of pieces into which eachfloating electrode is divided is not limited to four.

A method of manufacturing the touch panel 400 according to theembodiment of the present invention is described next with reference toFIGS. 5 to 13. FIGS. 5 to 8 illustrate sectional structures taken alongthe line B-B′ of FIG. 3 at various process stages. Similarly, FIGS. 9 to12 illustrate sectional structures taken along the line C-C′ of FIG. 3at various process stages.

A first step is described with reference to FIGS. 5 and 9.

In the first step, a first indium tin oxide (ITO) film 14 is formed onthe glass substrate 5 to have a thickness of about 15 nm, and then asilver alloy film 15 is formed to have a thickness of about 200 nm.

Next, a resist pattern is formed by photolithography process to patternthe silver alloy film 15.

The resist is removed and another resist pattern is formed byphotolithography process to pattern the first ITO film 14.

Thereafter, the resist is removed and the patterned ITO film 14 (Yelectrodes 2) and silver alloy film 15 (wiring lines 6) are formed asillustrated in FIGS. 5 and 9.

The silver alloy film 15 which is opaque has to be prevented from beingvisible. Then, the silver alloy film 15 is formed as only the peripheralwiring lines 6 by removing a part of the silver alloy film 15 thatoverlaps with the display region of the liquid crystal display panel600, which is overlaid later.

A second step is described next with reference to FIGS. 6 and 10.

In the second step, a photosensitive interlayer insulating film 16 isformed by application on the substrate on which the first ITO film 14and the silver alloy film 15 have been patterned. The interlayerinsulating film 16 is patterned through photolithography process. Theinterlayer insulating film 16 is desirably a film formed by applicationof a material that contains SiO₂ as the main component to have athickness of 1 μm or more.

As illustrated in FIG. 10, the contact holes 17 are formed in theperipheral portion. The interlayer insulating film pattern 16 is removedfrom a terminal connection portion which is used for a connection withan external drive circuit.

A third step is described next with reference to FIGS. 7 and 11.

In the third step, a second ITO film 18 is formed to have a thickness ofabout 30 nm and a resist pattern is formed by photolithography processto pattern the second ITO film 18.

The resist is then removed and the second ITO film 18 (X electrodes 1)is formed as illustrated in FIGS. 7 and 11.

A fourth step is described next with reference to FIGS. 8 and 12.

In the fourth step, the same kind of film as the insulating film used inthe second step is formed on the substrate by application as anuppermost protective film 19. The uppermost protective film 19 ispatterned by photolithography process.

The touch panel 400 is formed through the above-mentioned steps.

A brief description is given below on the operation of detecting aninput point of the touch panel 400 according to this embodiment.

In this embodiment, the touch panel control circuit 60 supplies aconstant current to the X electrodes 1 and the Y electrodes 2sequentially to charge the X electrodes 1 or the Y electrodes 2, and aperiod T required for the voltage of the X electrodes 1 or the Yelectrodes 2 to rise to a given reference voltage (Vref) is measured.

For example, in a state where the touch panel 400 is not being touchedby an observer's finger or the like, the period T is Ta as illustratedin FIG. 13. In a state where an observer's finger 35 or the like istouching the touch panel 400 as illustrated in FIG. 14, a capacitor (C)is added to the individual electrodes (1 b or 2 b) of the X electrodes 1or the Y electrodes 2, thereby setting the period T to Tb, which islonger than Ta (Ta<Tb).

The observer's finger 35 is generally larger than the area of theindividual electrode (1 b or 2 b) of one X electrode 1 or one Yelectrode 2. Accordingly, the period T that is longer than Ta (forexample, the period Tb) is detected in a plurality of X electrodes 1 ora plurality of Y electrodes 2. Based on the locations of a plurality ofelectrodes at which the period T that is longer than Ta is detected andthe length of the period (for example, Tb) detected in those electrodes,the centroid point is obtained by centroid processing as an input point.

The above-mentioned period T is detected from the count of basic clocks(e.g., dot clocks (CLKs) used in the liquid crystal display panel 600).

Therefore, “the capacitance of one line of the X electrodes and thecapacitance of one line of the Y electrodes” mentioned in the aspect (1)of the present invention also means a capacitance component of impedanceviewed from the touch panel control circuit 60. “The capacitance of oneline of the X electrodes and the capacitance of one line of the Yelectrodes are equal to each other” also means that the above-mentionedperiod T, or the count of dot clocks (CLKs) within the period T, isequal between the X electrodes and the Y electrodes.

Further, “the capacitance of one line of the X electrodes and thecapacitance of one line of the Y electrodes are equal to each other”means that the capacitance of one line of electrodes is within ±10% of adesigned value. Then, “the count of dot clocks (CLKs) within the periodT is equal between the X electrodes and the Y electrodes” naturallymeans that the dot clock count is within ±10% of a designed value.

The present invention can be applied irrespective of the shape of theinput detection region and the shape of the individual electrodes. Forexample, the present invention is applicable to a touch panel in whichthe X electrodes 1 and the Y electrodes 2 are formed in the same layeras illustrated in FIGS. 15 and 16.

In the touch panel illustrated in FIGS. 15 and 16, the individualelectrodes 1 b of the X electrodes 1 and the individual electrodes 2 bof the Y electrodes 2 are formed in the same conductive layer but areseparated from each other, whereas the intersection portions 1 a of theX electrodes 1 and the intersection portions 2 a of the Y electrodes 2are formed in different conductive layers.

In FIG. 16, the intersection portions 2 a of the Y electrodes 2 areformed in a layer above the intersection portions 1 a of the Xelectrodes 1 and intersect the intersection portions 1 a of the Xelectrodes 1 a. The intersection portions 2 a of the Y electrodes 2 areconnected to the individual electrodes 2 b of the Y electrodes 2 throughcontact holes 36 formed in the interlayer insulating film 16. FIG. 16 isa sectional view illustrating a sectional structure taken along the lineA-A′ of FIG. 15.

The embodiment above describes X direction electrodes and Y directionelectrodes which are orthogonal to each other. However, the presentinvention is aimed at averaging the difference in capacitance betweenelectrode lines used in the detection of an input point, and istherefore effective also for an adjustment of the capacitance betweenelectrodes that intersect each other obliquely, or between side-by-sideelectrode lines that have different lengths.

According to the present invention, a touch panel having an excellentdetection sensitivity can thus be manufactured as a capacitive inputdevice for an image information/text information display device.

While there have been described what are at present considered to becertain embodiments of the invention, it is understood that variousmodifications may be made thereto, and it is intended that the appendedclaim cover all such modifications as fall within the true spirit andscope of the invention.

What is claimed is:
 1. A touch panel comprising: X electrodes; and Yelectrodes which intersect the X electrodes; wherein the X electrodesand the Y electrodes respectively include: intersection portions eachformed where the X electrodes and the Y electrodes overlap each other;and individual electrodes each formed between the intersection portionsand being wider than the intersection portions; wherein a number of theindividual electrodes of the X electrodes is n and a number of theindividual electrodes of the Y electrodes is m; wherein an area of theindividual electrodes of the X electrodes is smaller than an area of theindividual electrodes of the Y electrodes if the number n is larger thanthe number m so that the individual electrode of the X electrodes isreduced in area with respect to an area of the individual electrode ofthe Y electrodes; and wherein a floating electrode is formed between theindividual electrode of the X electrode and the Y electrode, anddisposed outside of and around the area of the individual electrode ofthe at least one of the X electrodes and within a perimeter of an areawhich corresponds in area to the individual electrode of the one of theY electrodes.
 2. A touch panel according to claim 1, wherein either theX electrodes or the Y electrodes are made of a transparent conductivefilm.
 3. A touch panel according to claim 1, wherein both of the Xelectrodes and the Y electrodes are made of transparent conductive filmsthat sandwich an insulating film; and wherein the floating electrode ismade of a transparent conductive film.
 4. A touch panel according toclaim 1, wherein the floating electrode is smaller in area than theelectrode portion of the X electrode and the Y electrode.
 5. A touchpanel includes: a substrate including longer sides and shorter sides; Xelectrodes formed on the substrate; and Y electrodes which intersect theX electrodes; wherein the X electrodes are formed along the longer sideswhereas the Y electrodes are formed along the shorter sides; wherein theX electrodes and the Y electrodes respectively include: intersectionportions each formed where the X electrodes and the Y electrodes overlapeach other; and individual electrodes each formed between theintersection portions and being wider than the intersection portions;wherein each of the individual electrodes of the X electrodes is smallerin area than each of the individual electrodes of the Y electrodes sothat each of the individual electrodes of the X electrodes is reduced inarea with respect to an area of the individual Y electrode; and whereina floating electrode is formed between the individual electrode of the Xelectrode and the Y electrode, and disposed outside of and around thearea of the individual electrode of the at least one of the X electrodesand within a perimeter of an area which corresponds in area to theindividual electrode of the one of the Y electrodes.
 6. A touch panelaccording to claim 5, wherein either the X electrodes or the Yelectrodes are made of a transparent conductive film.
 7. A touch panelaccording to claim 5, wherein both of the X electrodes and the Yelectrodes are made of transparent conductive films that sandwich aninsulating film; and wherein the floating electrode is made of atransparent conductive film.
 8. A touch panel according to claim 5,wherein the floating electrode is smaller in area than the electrodeportion of the X electrode and the Y electrode.
 9. A touch panelcomprising: X electrodes which extend in a same direction; Y electrodeswhich extend in a direction different from the direction of the Xelectrodes; wherein the X electrodes and the Y electrodes respectivelyinclude: intersection portions each formed where the X electrodes andthe Y electrodes overlap each other; and electrode portions each formedbetween the intersection portions; wherein the electrode portions of atleast one of the X electrodes is smaller in area than the electrodeportions of one of the Y electrodes so that the electrode portion of theat least one of the X electrodes is reduced in area with respect to anarea of the electrode portion of one of the Y electrodes; and whereinfloating electrodes are formed close to the electrode portion of one ofthe X electrodes or the Y electrodes, and disposed outside of and aroundthe area of the electrode portion of the at least one of the Xelectrodes and within a perimeter of an area which corresponds in areato the electrode portion of the one of the Y electrodes.
 10. A touchpanel according to claim 9, wherein either the X electrodes or the Yelectrodes are made of a transparent conductive film.
 11. A touch panelaccording to claim 9, wherein both of the X electrodes and the Yelectrodes are made of transparent conductive films that sandwich aninsulating film; and wherein the floating electrodes are made of atransparent conductive film.
 12. A touch panel according to claim 9,wherein the floating electrodes are smaller in area than the electrodeportion of the X electrode and the Y electrode.